During a manufacturing process of semiconductor devices, various features are sequentially formed on a wafer resulting in an increasingly non-planar surface of the wafer. Such a non-planar surface is planarized to improve quality and/or uniformity of features subsequently formed on the wafer. Chemical mechanical polishing (CMP) is a wafer processing technique that is used to planarize surfaces of wafers. A CMP process removes excess materials, such as dielectric and/or conductive layers, from a surface of a wafer. The planarization operation leaves contaminants, such as residues of the removed materials, on the planarized surface. A brush cleaning operation is performed to remove such contaminants from the planarized surface, readying the wafer for subsequent processing.